The aim of this proposal is to evaluate the feasibility of developing analytical technology applicable to the determination of desmosine (DMS) in the systematic circulatory system and in other physiological samples. In vivo hydrolytic degradation of the connective tissue elastin by the enzyme elastase produces DMS-peptide fragments. Current results form biomedical and pharmaceutical research suggest that an accurate determination of DMS-peptide levels in vivo may serve as a useful indicator of elastase activity. Unregulated elastase activity has been implicated in pulmonary complications in diseases such as emphysema and cystic fibrosis. As such, technology to be developed here is essential for the evaluation of the effectiveness of newly designed elastase inhibitors. Moreover, the information generated will be useful in the design of a diagnostic system for the detection of the onset of some pulmonary diseases. The strategy to the development of assay technology with the appropriate selectivity and sensitivity will be derived from a fundamental understanding of the physicochemical properties of DMS and DMS-peptide fragments. Because current findings suggest that DMS exists in the biological media as multiple peptide fragments, technologies need to be developed to pool these fragments followed by hydrolysis, identification and quantification. Special chromatographic and detection techniques, such as high performance ion-exchange and ion-pair chromatography, and chemical derivatization, will be explored.